Printing apparatus and device manufacturing method

ABSTRACT

The printing apparatus, presented herein, comprises a patterning device having a curved member that supports a stamp on its surface. The curved member is adapted to roll over a substrate to be printed on to transfer the pattern onto the substrate. An illumination system directs light onto the region of the substrate that is being printed in order to set a layer of resist, which has been sprayed onto the substrate. The light is directed via a pattern that is made on the surface of the stamp, thereby transferring the pattern to the substrate.

RELATED APPLICATION

The present application is a Continuation In Part Application of U.S.application Ser. No. 10/792,267, filed on Mar. 4, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a printing apparatus and a devicemanufacturing method.

2. Description of the Related Art

Lithographic apparatus can be used, for example, in the manufacture ofintegrated circuits (ICs). In such a case, a patterning device may beused to generate a desired circuit pattern corresponding to anindividual layer of the IC, and this pattern can be imaged onto a targetportion (e.g. comprising one or more dies) on a substrate (siliconwafer) that has been coated with a layer of radiation-sensitive material(resist).

In general, a single substrate will contain a network of adjacent targetportions that are successively exposed. Known lithographic apparatusinclude so-called steppers, in which each target portion is irradiatedby exposing an entire pattern onto the target portion in one go, andso-called scanners, in which each target portion is irradiated byscanning the pattern through the projection beam in a given direction(the “scanning”-direction) while synchronously scanning the substrateparallel or anti-parallel to this direction.

A known method of imparting a pattern onto a substrate includes applyinga stamp vertically onto a substrate covered in resist, illuminating thestamp to set exposed resist or light sensitive material and verticallylifting the stamp off the substrate. Lithographic techniques are oftenused for such nanometer scale printing on substrates for flat paneldisplays and the like.

SUMMARY OF THE INVENTION

The principles of the present invention, as embodied and broadlydescribed herein, provide a patterning device that is less expensive tocreate and use than known methods. In one embodiment, a printingapparatus for nanometric scale imprinting is provided comprising acurved member for supporting a stamp, the curved member being adapted toroll over a substrate to be printed on, and the stamp having a patternin its surface, and an illumination system for directing light to aregion of contact between said stamp and said substrate.

An advantage of rolling the curved member over the substrate, ratherthan vertically applying a stamp is that while the curved memberrotates, is that the distance between the stamp and the substrate ismaintained. Because it is a rolling process rather than a verticalstamping process, the throughput of substrates can be higher since thestamp does not have to stop at any time—in other words, it can continueto roll at a steady rate as long as the stamp patterns on the surface ofthe curved member are placed with a separation consistent with theseparation of substrates coming into the process device.

Furthermore, a vertically applied stamp is limited in its speed ofapplication because of the risk of damaging substrates. The rolling ofthe curved member eliminates the risk of damage caused by impact andremoval of a vertically applied stamp. Also, another advantage ofrolling the curved member over the substrate is that a more uniformdistribution of the resist or light sensitive material is enabled by thecontrol of the gap between the substrate and the stamp. Thepredetermined gap between the substrate and the stamp may be maintainedwhile the curved member is rolled over the substrate, whereas with avertically applied member, there is more scope for variation in the gapsize and therefore in thickness of the resist. The curved member may besaid to supply a steamroller effect to the resist.

In addition, the application of a curved member means that the removalof the stamp from the substrate is much smoother than verticallyremoving the stamp from the resist. There is less of a risk of damagingthe patterned resist layer.

Moreover, the curved member need not be rolled continuously, as it couldbe swung back and forth over the substrate, giving the effect of beingrolled over the substrate, but in two directions rather than just theone.

The curved member may have a triangular cross section with curved sides,for example, the curved member may be the shape of a Wankel motor. Theadvantage of this shape over a standard cylinder is that the size of thecurved member can be reduced while the radius of curvature of the stampis kept large enough to cover the target portion of the substrate.

The illumination system may be located inside the curved member. Thisaffords the advantage of keeping the illumination means in a centrallocation in the curved member so that no matter which side of the memberis facing the substrate, the illumination means is illuminating thesubstrate via the stamp on the surface of the curved member.Alternatively, the illumination means could be on the outside of thecurved member with means to illuminate the target area.

There are preferably thermal elements for controlling the temperature ofthe curved member to align the stamp with the target portion of thesubstrate and for correcting the magnification of the pattern on thestamp. Magnification of the pattern may be adjusted by stretching orcompressing the stamp or the substrate. The pattern is set onto thesubstrate with the correct alignment and at the correct magnification,otherwise the substrate will not be able to serve its purpose. Theborder of the stamp and/or the substrate can be constantly monitored andthe thermal elements may be used either in the substrate or the stamp toadjust the relative positions and magnifications, even “on the fly”.

The stamp may be made of glass and comprise a patterned layer on itssurface. The advantage of using glass is that it allows the illuminationin this case to pass through the unpatterned sections of the glass. Thestamp may alternatively be made of quartz glass or any material thatallows the illumination radiation to be transmitted to the resist whilebeing formable into the curved member shape.

There is preferably provided a resist provider for providing a layer ofresist on the target portion of the substrate and the resist ispreferably a liquid that sets when illuminated. The resist may besprayed onto the substrate before the introduction of the stamp. Theremay also be a release agent provided on the surface of the stamp inorder to release the stamp from the resist without damaging the patternor resist layer.

There are usefully alignment markers along the stamp for aligning withmarkers along the substrate. This allows the rolling curved member andthe stamp on its surface to maintain its alignment with the substrate sothat the pattern is imparted to the target portion of the substrate.

According to a further aspect of the invention, there is provided adevice manufacturing method comprising providing a substrate, providinga layer of resist on a target portion of the substrate, providing a beamof radiation using an illumination system, providing a curved memberwith a pattern on its surface, rolling the curved member over thesubstrate, and projecting the beam of radiation onto the resist.

Although specific reference may be made in this text to the manufactureof flat panel displays, it should be understood that the printingapparatus described herein may have other applications, such as themanufacture of integrated optical systems, guidance and detectionpatterns for magnetic domain memories, liquid-crystal displays (LCDs),thin-film magnetic heads, etc. The skilled artisan will appreciate that,in the context of such alternative applications, any use of the term“wafer” herein may be considered as synonymous with the more generalterm “substrate”.

The substrate referred to herein may be processed, before or afterexposure, in for example a track (a tool that typically applies a layerof resist to a substrate and develops the exposed resist) or a metrologyor inspection tool. Where applicable, the disclosure herein may beapplied to such and other substrate processing tools. Further, thesubstrate may be processed more than once, for example in order tocreate a multi-layer IC, so that the term substrate used herein may alsorefer to a substrate that already contains multiple processed layers.

The terms “radiation” and “beam” used herein encompass all types ofelectromagnetic radiation, including ultraviolet (UV) radiation (e.g.having a wavelength of 365, 248, 193, 157 or 126 nm) and extremeultra-violet (EUV) radiation (e.g. having a wavelength in the range of5-20 nm).

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying schematic drawings in whichcorresponding reference symbols indicate corresponding parts, and inwhich:

FIG. 1 depicts a printing apparatus in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION Embodiments

FIG. 1 depicts substrates 20 being introduced into the patterningdevice. The curved member 25 includes a patterning stamp 30 on itssurfaces, which contains a desired pattern. The curved member 25 isrolled over the substrates 20. Each patterning stamp 30 on the surfacesof the curved member 25 is configured to be the correct size to printthe desired pattern onto a single substrate 20. As the patterning stamp30 rolls over a substrate 20, the illumination means 10 illuminates thesubstrate via the patterned surface 30.

Exposure radiation 15 is the illumination radiating in the correctdirection in order to set the resist via the stamp pattern. The resiston the substrate 20 sets where the pattern allows the exposure radiation15 to be transmitted through the curved member 25 surfaces. The system,in some ways, is analogous to a newspaper printing system except thatinstead of a round cylinder, a Wankel motor-shaped cylinder is used. Inthis manner, the surfaces of the curved member 25 are able to have aradius of curvature grater than the radius of an equivalently sizedcylinder.

The patterning stamp 30 is made of patterned glass or quartz glass. Thepattern might be etched into the glass or bonded to it and might becovered with non-adhesive/non-sticking or “release” layers. The glassmay be patterned and then bent into the cylinder shape or vice versa.

The illumination means 10 emits radiation suitable for setting theresist, which may be sprayed onto the substrates 20 before they enterthe device. The contact between the curved member 25 and the substrate20 is “soft”; i.e. there is a gap of several nm.

The resist, which may comprise, although not exclusively, a polymer, maybe sprayed onto the substrate 20. As such, the resist may be in liquidform until it is exposed to the exposure radiation 15, at which point itsets to a solid, with any unset resist being removable by a releaseagent.

The application of the resist in its liquid form may be performed eitherbefore the imprinting step, during an independent step, or just beforethe stamping takes place. In the latter case, the liquid may bedispensed in a tightly controlled fashion (i.e., in nanolitre-sizeddroplets) by means of a line of droplet-releasing units, creating avirtual shower of resist 37 just before the stamping, as depicted byunit 35 in FIG. 1.

The substrate 20 is a glass panel in the case of the manufacture of flatpanel displays, though it may also be plastic or silicon. The substrate20 is preferably the same size as the stamp in order to enable the moreefficient alignment of the stamps and substrates.

There are preferably thermal elements for controlling the temperature ofthe curved member 25 to align the patterning stamp 30 with the targetportion of the substrate and for correcting the magnification of thepattern on the stamp 30. The pattern must be set onto the substrate 30with the correct alignment and at the correct magnification, otherwisethe substrate 20 will not be able to serve its purpose. The border ofthe stamp 30 and/or the substrate 20 can be constantly monitored and thethermal elements may be used either in the substrate 20 or the stamp 30to adjust the relative positions and magnifications, even “on the fly.”

In order to ensure that the pattern is correctly imprinted onto thetarget portion of the substrate 20, alignment markers are printed alongthe edges of the stamp 30, which are aligned with markers in scribelanes along the edge of the substrate 20.

Magnification of the pattern may be adjusted by stretching orcompressing the stamp 30 or the substrate 20. In order to control themagnification of the pattern, the stamp 30 or the substrate 20 can bestretched in the range of a few parts per million.

Whilst specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. As such, the description is not intended to limit theinvention.

The configuration, operation, and behavior of the present invention hasbeen described with the understanding that modifications and variationsof the embodiments are possible, given the level of detail presentherein. Thus, the preceding detailed description is not meant orintended to, in any way, limit the invention—rather the scope of theinvention is defined by the appended claims.

1. A printing apparatus, comprising: a curved member carrying a stampsurface having a plurality of separate curved sides that form aperiphery of the curved member, each of said curved sides defining aconvex surface that intersects with two other of said curved sides, andeach of said curved sides including a pattern, the curved member beingconfigured, in use, to roll over a substrate with a layer of resist toprint the pattern on a target portion of the substrate, wherein, as saidcurved member rolls over said substrate, said pattern of each of saidcurved sides remains stationary relative to each of said curved sides; aresist mechanism configured to provide a liquid layer of the resist onthe target portion of the substrate; and an illumination systemconfigured to direct light to a region of contact between the stampsurface and the target portion of the substrate.
 2. The apparatus ofclaim 1, wherein said curved member has a triangular cross section withcurved sides.
 3. The apparatus of claim 1, wherein said illuminationsystem is located inside said curved member.
 4. The apparatus of claim1, further comprising thermal elements configured to control temperatureof said curved member, to align said stamp surface, and to correctmagnification of said stamp surface.
 5. The apparatus of claim 1,wherein said stamp surface is comprised of glass.
 6. The apparatus ofclaim 1, wherein said resist mechanism provides said liquid layer ofresist by spraying said liquid layer of the resist in a shower-likeconfiguration.
 7. The apparatus of claim 1, wherein the liquid layer ofresist sets when illuminated.
 8. The apparatus of claim 1, furthercomprising alignment markers along said stamp surface configured toalign with markers along said substrate.
 9. The apparatus of claim 1,wherein the curved member has a shape of a Wankel motor-shaped cylinder.10. A printing apparatus for nanometric scale imprinting, comprising: acurved member carrying a stamp surface having a plurality of separatecurved sides that form a periphery of the curved member, each of saidcurved sides defining a convex surface that intersects with two other ofsaid curved sides, and each of said curved sides including a pattern,the curved member being configured, in use, to roll over a substratewith a layer of resist to print the pattern on a target portion of thesubstrate, wherein, as said curved member rolls over said substrate,said pattern of each of said curved sides remains stationary relative toeach of said curved sides; a resist mechanism that provides said layerof resist by spraying said layer of resist in a shower-likeconfiguration on said target portion of the substrate; and anillumination system configured to direct light onto a region where saidstamp surface has contacted said layer of resist on said substrate. 11.The apparatus of claim 10, wherein said curved member has a triangularcross section with curved sides.
 12. The apparatus of claim 10, whereinsaid illumination system is located inside said curved member.
 13. Theapparatus of claim 10, further comprising thermal elements configured tocontrol the temperature of said curved member.
 14. The apparatus ofclaim 10, wherein said stamp surface is comprised of glass.
 15. Theapparatus of claim 10, further comprising alignment markers along saidstamp surface configured to align with markers along said substrate. 16.The apparatus of claim 10, wherein the curved member has a shape of aWankel motor-shaped cylinder.